The known winches of this kind are most often equipped with at least two drums arranged so as to be spaced from each other and parallel to each other. A wire rope is slung about the rope drums and is guided in grooves formed on the peripheral surface of the rope drums. Both rope drums are driven by a motor via a corresponding branching gear transmission. One of the two rope drums has a run-out groove for the rope which is bounded by a tightening disc. This tightening disc is configured so that it is pressable against the one side of the rope.
The rope to which the load is attachable, can be run out via the drive motor which most often is configured as an oil motor and by means of corresponding switching of the transmission. If the rope is unloaded so that no load is suspended from the rope, the rope must be pulled out by hand. If this does not happen, the rope runs against a hydraulic contact switch which actuates a hydraulic valve. Hydraulic oil is transmitted into a piston-cylinder displacement unit through the hydraulic valve. The tightening disc is pulled away from the cable rope via the displacement unit whereby the force flow or frictional engagement is interrupted. The hydraulic piston-cylinder displacement unit is most expensive and difficult to produce because tight tolerances and precise workmanship must be maintained.
A further disadvantage is that, for example, because of inadequate sealing in the hydraulic displacement unit, the operational reliability is affected so that a large residual frictional engagement remains in the region of the run-out groove so that this can lead to the undesired formation of loops when the rope is run out. Such a formation of loops can often not be prevented also with respect to a dirty rope because of the frictional engagement conditions utilized in the region of the run-out groove.